There seems to be misunderstanding about stress test and reasons why to go and see cardiologist in regards to exercise. It is prudent to check if you have any issue with heart before trying to do any heavy exercise. Usual EKG done in Dr office is done while you are resting and it may be normal. Some of the problems only show while you are exercising and that is why you do stress test. During the test usually done on treadmill load will be incrementally increased which cause higher HR. There is a point when HR reaches plateau and even if you increase the load, it will not go higher. That is your maxHR. Very seldom in normal life you hit that point. When you know your maxHR and your resting HR, you can calculate zones (levels) for your training. It is prudent to do stress test every 5-7 years or so to make sure that you dont hurt yourself. This was a recommendation for anyone over 40 from the company I worked for. Sort of insurance policy, preventive measure.